its still worth going, but they are probably the worst seats.
your kids im sure wont care. personally for me, if you can afford it, the seats in the section behind the basket tend to be just a little bit more . granted the sight lines are awful, but the cheapest close bottom level is always behind a basket.
i've bought tons of tickets on ebay by the way, mostly from sellers with lots of feedback. some of them wont email the pdfs anymore and require shipping due to the idiotic way ebay does guarantees and such.
but never have had an issue buying tickets there, most of those are just local ticket shops anyway.